Breech obturating means for gun with transversely slidable breechblock



Dec. 5, 1967 G. DANDREA 3,355,986

BREECH OBTURATING MEANS FOR GUN WITH TRANSVERSELY SLIDABLE BREECHBLOCK Filed April 21, 1966 3 Sheets-Sheet 1 I I I I I I I I I I Q I w m l I I I I I I 1 I I l l I I I l g I I I co I I (\J I l g I" INVENTOR Exiulitmu 1] 'AnEIren.

ATTORNEY Dec. 5, 1967 G. DANDREA 3,355,986

BREECH OBTURATING MEANS FOR GUN WITH TRANSVERSELY SLIDABLE BREECHBLOCK Filed April 21, 1966 5 Sheets-Sheet 2 INVEENTOR Giuliunl: 1] Andrea ATTORNEY Dec. 5, 1967 G. DANDREA 3,355,986

BREECH OBTURATING MEANS FOR GUN WITH TRANSVERSELY SLIDABLE BREECHBLOCK Filed April 21, 1966 s Sheets-Sheet 5 INVENTIOR Eriu'liunn II ATlflTEII.

' BMW ATTORNEY United States Patent Ofiice 3,355,986 Patented Dec. 5, 1967 3,355,986 BREECH OBTURATING MEANS FOR GUN WITH TRANSVERSELY SLIDABLE BREECHBLOCK Giuliano DAndrea, Troy, N.Y., assignor to the United States of America as represented by the Secretary of the Army Filed Apr. 21, 1966, Ser. No. 545,518 8 Claims. (Cl. 89-24) ABSTRACT OF THE DISCLOSURE In order to obturate the breech of a large caliber gun in which the firing chamber is separately contained in a laterally slidable breechblock, a sealing ring is provided on the rear end of a tubular carrier slidably seated within the breech end of the gun tube. The gear mechanism which actuates the breechblock to open and close the breech is also utilized to rotate the carrier so that a cam path formed along the exterior surface thereof imparts corresponding longitudinal movement thereto designed to actuate the sealing ring into and out of obturating engagement with a mating counterbore surrounding the forward end of the firing chamber. In addition, the exterior periphery of the sealing ring is specifically contoured to provide equal obturation on both sides of the interface between the rear end face of the carrier and the front face of the breechblock.

This invention relates to artillery of the type wherein a gun tube and a separate firing chamber contained in a transversely slidable breech closing member combine to form a recoiling breech and is more particularly directed to improved means for obturating the joint between the gun tube and the firing chamber whenever the breech is fully closed.

Although cannon of large caliber are extremely effective ground weapons, the utilization thereof in modern warfare is steadily decreasing primarily due to the relatively low rate of sustained fire which can be attained with the designs in current use. This is particularly true in those guns wherein the ammunition therefor consists of separate projectiles and powder charge-s which must be brought into axial alignment before firing can be initiated. However, in a recent redesign of a howitzer type weapon, it has been demonstrated that the time required to position a separate projectile and powder charge into axial firing alignment can be drastically reduced. This accelerated loading of the ammunition therein has been accomplished by utilizing a transversely slidable breechblock to effect the opening and closing of the breech and attaching a projectile loading tray to one end of such breechblock for corresponding movement therewith in the transverse direction. However, the attachment between the loading tray and the breechblock is such that the latter is free to recoil and counter recoil independently of the loading tray. Thus, as the breechblock is actuated to open the breech, the leading projectile in the loading tray will be simultaneously advanced into position to be rammed forwardly into the gun tube. In addition, the breechblock is provided with a forwardly opening firing chamber which will move exteriorly of the receiver during the opening of the breech so as to be exposed for the loading of a powder charge therein. Consequently, as the breechblock is returned to the breech closing position thereof, the powder charge will be simultaneously advanced into firing alignment with the projectile which had been rammed into the gun tube.

One of the problems associated with this new breech mechanism has been the difficulty encountered in effectively obturating the junction between the breech end of the tube and the front face of the firing chamber in the breechblock during the portion of the operating cycle in which the breech is fully closed. In view of the necessity for unobstructed transverse movement of the breechblock, the customary compressible type of breech seal cannot be advantageously utilized. Furthermore, the necessity for avoiding any interference with the loading of powder charges into the firing chamber precludes the usual mounting of the seal on the breech opening and closing member.

It is therefore a general object of this invention to provide improved breech obturating means for a large caliber gun having a recoiling breech and a transversely reciprocal breechblock for effecting the opening and closing of the breech.

Another object of this invention is to provide a breech seal for the aforesaid gun adapted to be carried by an extension of the breech end of the gun tube.

A further object of this invention resides in the provision of a breech seal adapted to be cycled by the same mechanism utilized to reciprocate the transversely slidable breechblock for closing and opening the breech.

Still another object of the present invention is to provide a breech sealing mechanism as aforesaid which does not require a compressible sealing member.

A specific object of this invention is to provide a seal which will impart positive obturation to the interface between the rear end of the gun tube extension and the front face of the breechblock without interfering with the transverse breech opening and closing governments therefor.

It has been found that these objects can best be achieved by a metallic sealing ring fixedly secured to the rear end of a cam-operated tubular carrier which is in turn slidably mounted for longitudinal reciprocation in a rearward extension of the gun tube. A follower is fixedly secured within the interior of the gun tube extension to project into slidable engagement with a cam track circumferentially formed in the exterior periphery of the carrier. In addition, a circular gear surrounds the exterior of the carrier in meshing engagement with a gear mechanism which is in turn engageable with the gear rack utilized to transversely reciprocate the breechblock for opening and closing the breech. Thus, as the carrier is reversibly rotated in direct response to the transverse reciprocation of the gear rack, the configuration of the cam track actuates the carrier to reciprocate the sealing ring thereon into and out of obturating engagement with the interior of the firing chamber in the transverse breechblock during the interval in which the breech is fully closed. As a result, the interface between the rear end of the obturator and the front face of the breechblock can be effectively sealed to provide corresponding obturation of the interface between the breech end of the gun tube extension and the front face of the breechblock. Furthermore, this is accomplished without the use of the compressible materials heretofore employed for this purpose which cannot withstand the extremely high temperatures and pressures encountered in the firing chambers of large caliber guns. In addition, the required obturation is achieved without any interference with the transverse reciprocation of the breechblock.

Further objects and features of the invention will be apparent from the following specification and the accompanying drawings which are for the purpose of illustration only and in which:

FIG. 1 is a fragmentary side view of the breech portion of a large caliber gun with the forward section thereof cut away to show the sealing ring assembly in the interior of the gun tube extension;

FIG. 2 is a sectional view taken along line 2-2 in FIG. 1 to show the gearing arrangement utilized to rotate the sealing ring carrier;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1 to show the rack gear employed to actuate the gearing arrangement of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 in FIG. 2 but on an enlarged scale showing the sealing ring in the non-obturating position assumed prior to the ramming of a projectile into the gun tube; and

FIG. 5 is a view similar to that of FIG. 4 but showing the sealing ring in the obturating position imparted thereto upon the locking of the breechblock in the closed breech position thereof.

Referring to the drawings and particularly to FIG. 1 there is shown a portion of a large caliber gun of the howitzer type wherein a tube 12 is threadably secured as indicated at 16 to a rearward extension 14 which is in turn threadably mounted in the forward end of a recoiling receiver 18 slidably contained in a stationary frame 19. A rectangular breechblock 20 is slidably seated in the forward end of receiver 18 for transverse movement into and out of a breech closure position. As more fully described in my copending application Ser. No. 533,379, filed Mar. 3, 1966, and entitled Sliding Breech Operating Mechanism for Large Caliber Gun, the required transverse reciprocation of breechblock 20 and the locking thereof in the closed breech position is eected by a pair of pivotal levers 22 actuated by gearing which includes a rack 24 slidably mounted in a T-shaped channel 26 extending transversely across the top of receiver 18. Rack 24 is in turn transversely reciprocated by a hydraulic actuator 28 which is releasably connected thereto to permit the required recoil and counter recoil movement of receiver 18.

As best shown in FIG. 3, the underside of gear rack 24 is formed with gear teeth 30 which mesh with a pinion gear 32 mounted therebelow on the rear end of a longitudinal rod 34 rotatably housed in the upper wall of receiver 18. A driving gear 36 is secured to the forward end of rod 34 in meshing engagement with an intermediate gear 38 mounted on a longitudinally extending axle 40 rotatably seated in the breech end of gun tube extension 14. Gear 38 is in turn disposed for meshing engagement with gear teeth 42 encircling the rear end of a sealing ring carrier 44 slidably seated in the interior of gun tube extension 14.

Carrier 44 is a tubular member of smaller length than the distance between the breech end of gun tube 12 and the front face of breechblock 20 in the closed breech position thereof. The interior periphery of carrier 44 is forwardly tapered as indicated at 46 in FIG. 4 to facilitate the ramming of a projectile 48 into gun tube 12 and to direct the discharge gases into a forward flow against the base of projectile 48. A sealing ring 50 is fixed within the interior of carrier 44 by suitable screws 52 to partially project from the rear end thereof. Forwardly of gear teeth 42 and adjacent thereto, carrier 44 is reduced in diameter to form a peripheral band 54. The interior periphery of gun tube extension 14 at the rear end thereof is diametrically stepped as indicated at 56 and 58 to respectively accommodate gear teeth 42 and peripheral band 54.

As best shown in FIG. 1, a cam track 60 is formed into the exterior periphery of band 54 and extends circumferentially therearound to terminate in a forwardly curved open end 62 spaced from the opposite and closed end thereof (not shown). A follower stud 64 is threadably fixed in the breech end of gun tube extension 14 and is provided with a cylindrical head 66 which projects into the interior of extension 14 into slidable engagement with cam track 60.

Thus, when gear rack 24 is actuated to return breechblock 20 to the closed breech position thereof. pinion gear 32 is rotated to impart corresponding rotation to driving gear 36 and thereby through intermediate gear 38 to carrier 44. Carrier 44 remains stationary within the breech end of gun tube 12 until the curved portion of cam track 60 moves into engagement with fixed follower head 66 whereupon the interaction therebetween cams carrier 44 rearwardly in gun tube extension 14 to position sealing ring 50 into a mating counterbore 68 in the forward end of a cylindrical firing chamber 70 provided in breechblock 20 for axial alignment with gun tube 12 when the breech is fully closed. In this position, as best shown in FIG. 5, the exterior periphery of sealing ring 50 overlies the interface between the rear end of carrier 44 and the front face of breechblock 26 while the rear face of sealing ring 50 abuts the annular surface area formed by counterbore 68 in firing chamber 70. In order to effect maximum obturation of firing chamber 70 upon the discharge of powder charge 72, the exterior periphery of sealing ring 50 is circumferentially notched to form a triangular tooth 74 disposed for alignment with the circumferential dividing line between carrier 44 and breechblock 20. Experience has shown that a relatively thin beveled edge is of considerably greater effectiveness than a linear surface in blocking the entry of discharge gases into the space which may exist between contact surfaces as a result of the tolerances utilized in the manufacture of the component parts. If desired, the breech may be additionally sealed by the provision of a plurality of concentric grooves 76 formed about the exterior periphery of carrier 44 adjacent the forward end thereof.

Accordingly, the present invention provides a positive and efficient means of obturating the interface between a breechblock and the breech end of a gun tube or extension thereof which is far superior to the flexible nonmetallic seals heretofore used for this purpose. Inasmuch as the breach seal is not carried by the transversely reciprocal breechblock and is operative only during the interval in which the latter is completely stationary, there is no interference whatsoever with the opening and closing of the breech. Furthermore, the concept of utilizing the apex of a triangular tooth circumferentially formed about the exterior periphery of a sealing ring to obturate the joint between the breechblock and the carrier on which the ring is mounted is a considerable improvement over the customary reliance on the surface area provided by the front face of a flexible ring seal. The primary benefit of a longitudinally slidable sealing member is, of course, the ability to utilize a sealing configuration which can be positioned to provide equal obturation on both sides of the interface in direct ratio to the pressure produced by the expanding discharge gases.

The present invention has been described in detail above for the purpose of illustration only and is not intended to be limited by this description or otherwise except as defined by the scope of the appended claims.

I claim:

1. In a large caliber gun having a recoiling receiver, a gun tube fixedly mounted in the receiver, a breechblock slidably disposed in the receiver for effecting transverse closure of the breech end of the gun tube, and a forwardly opening firing chamber in the breechblock disposed for axial alignment with the gun tube when the breech thereof is fully closed, means for obturating the interface between the breechblock and the gun tube comprising a tubular sealing ring carrier slidably seated within the breech end of the gun tube for longitudinal reciprocal movement, a sealing ring fixedly projecting from the rear end of said carrier, gear means in the receiver responsive to the transverse movement of the breechblock for imparting corresponding rotation to said carrier, and cam means on said carrier for imparting reciprocal movement thereto during the rotation thereof whereby said sealing ring is actuated into and out of obturating contact with the front face of the breechblock.

2. In a large caliber gun having a receiver slidably mounted for longitudinal recoil and counter recoil movement, a gun tube having the breech end thereof fixedly retained in the forward end of the receiver, a breechblock slidably mounted in the receiver for transverse reciprocal movement to open and close the breech end of the gun tube, and a forwardly opening firing chamber disposed in the breechblock for axial alignment with the gun tube when the breech end thereof is fully closed, means for obturating the interface between the breechblock and the gun tube comprising a tubular sealing ring carrier slidably seated within the breech end of the gun tube for longitudinal reciprocal movement, a sealing ring fixedly mounted in the rear end of said carrier in position to project rearwardly therefrom, the firing chamber being counterbored at the front end thereof to receive the projecting rear end of said sealing ring, gear means mounted in the receiver for rotating said carrier in direct response to the transverse reciprocation of the breechblock, and cam means responsive to the rotation of said carrier for imparting longitudinal reciprocal movement thereto into and out of contact with the front face of the breechblock whereby said sealing ring is actuated into and out of obturating contact with the annular counterbored area surrounding the forward end of the firing chamber and with the interface between the rear end of said carrier and the front face of the breechblock.

3. The combination defined in claim 2 wherein said cam means comprises a track circumferentially encircling said carrier to terminate in a forwardly curved cam portion at one end thereof, and a follower stud fixed in the receiver in position to extend into said track for contact with said cam portion thereof during the rotation of said carrier.

4. The combination defined in claim 2 wherein the exterior periphery of the projecting rear end of said sealing ring is circumferentially notched to form a triangular tooth positioned to align with the interface between said carrier and the front face of the breechblock when said sealing ring is oburatingly disposed in said counterbored front end of the firing chamber.

5. The combination defined in claim 2 wherein said gear means comprises a gear rack slidably mounted in the top of the receiver for transverse movement thereacross, a longitudinally extending rod journaled in the forward end of the receiver, a first gear secured to the rear end of said rod in meshing engagement with said gear rack, a second gear secured to the forward end of said rod, an intermediate gear rotata-bly mounted in the receiver in meshing engagement with said second gear, and a gear ring encircling the rear end of said carrier in meshing engagement with said intermediate gear whereby the transverse reciprocation of said gear rack rotates said journaled rod to impart corresponding rotation to said carrier.

6. In a large caliber gun having a stationary frame, a receiver slidably mounted on the frame for longitudinal recoil and counter recoil movement, a gun tube having a rearward extension secured thereto for threaded retention in the forward end of the receiver, a breechblock having 6 a forwardly opening longitudinal firing chamber therein,

and an externally driven gear rack for transversely reciprocating the breechblock to axially align the firing chamber with the breech end of the gun tube, means for obturating the interface between the breech end of the gun tube extension and the front face of the breechblock when the breech end of the gun tube is closed comprising, a tubular sealing ring carrier slidably seated within the breech end of the gun tube extension for longitudinal reciprocal movement, a sealing ring fixedly mounted in the rear end of said carrier in position to project rearwardly therefrom, the firing chamber being counterbored at the forward end thereof to slidably receive the projecting rear end of said sealing ring, gear means disposed in the receiver in simultaneous engagement with the externally driven gear rack and said carrier whereby the transverse reciprocation of the former is utilized to impart reversible rotation to the latter, a circumferential track formed about the exterior periphery of said carrier and terminating in a forwardly curved cam portion, and a follower stud fixed in the breech end of the gun tube extension in position to extend into said circumferential track whereby rotation of said carrier in one direction cams said sealing ring rearwardly into obturating contact with the annular surface area surrounding the firing chamber within the counterbored front end thereof, the peripheral area of the sea-ling ring thereby straddling the interface between said carrier and the front face of the breechblock to obturate the interface between the breechblock and the gun tube extension, and whereby rotation of said carrier in the opposite direction cams said sealing ring forwardly out of obturating engagement in the breechblock to permit subsequent unobstructed opening of the breech end of the gun tube.

7. The combination defined in claim 6 wherein the exterior periphery of said carrier is diametrically enlarged to contain said circumferential track and is additionally enlarged rearwardly thereof to mount a ring gear disposed for meshing engagement with said gear means in the receiver, and wherein the gun tube extension is double counterbored at the rear end thereof to provide access for the enlarged diameter portions of said carrier.

8. The combination defined in claim 6 wherein the gun tube is adapted for the loading of a projectile therein, the interior of the firing chamber is adapted for the discharge of a powder charge, and the interior of said carrier is forwardly sloped to channel the discharge gases against the rearward portion of the projectile.

References Cited UNITED STATES PATENTS 2,480,100 8/1949 Weiss et al. 89-26 X 3,006,254 10/ 1961- Thierry 89-26 3,141,377 7/1964 Butterworth 8926 X 3,303,744 2/1967 Lanizzani 89-155 X FOREIGN PATENTS 15,309 1911 Great Britain.

BENJAMIN A. BORCHELT, Primary Examiner. S. C. BENTLEY, Assistant Examiner. 

1. IN A LARGE CALIBER GUN HAVING A RECOILING RECEIVER, A GUN TUBE FIXEDLY MOUNTED IN THE RECEIVER, A BREECHBLOCK SLIDABLY DISPOSED IN THE RECEIVER FOR EFFECTING TRANSVERSE CLOSURE OF THE BREECH END OF THE GUN TUBE, AND A FORWARDLY OPENING FIRING CHAMBER IN THE BREECHBLOCK DISPOSED FOR AXIAL ALIGNMENT WITH THE GUN TUBE WHEN THE BREECH THEREOF IS FULLY CLOSED, MEANS FOR OBTURATING THE INTERFACE BETWEEN THE BREECHBLOCK AND THE GUN TUBE COMPRISING A TUBULAR SEALING RING CARRIER SLIDABLY SEATED WITHIN THE BREECH END OF THE GUN TUBE FOR LONGIDUAINAL RECIPROCAL MOVEMENT, A SEALING RING FIXEDLY PROJECTING FROM THE REAR END OF SAID CARRIER, GEAR MEANS IN THE RECEIVER RESPONSIVE TO THE TRANSVERSE MOVEMENT OF THE BREECHBLOCK FOR IMPARTING CORRESPONDING ROTATION TO SAID CARRIER, AND CAM MEANS ON SAID CARRIER FOR IMPARTING RECIPROCAL MOVEMENT THERETO DURING THE ROTATION THEREOF WHEREBY SAID SEALING RING IS ACTUATED INTO AND OUT OF OBTURATING CONTACT WITH THE FRONT FACE OF THE BREECHBLOCK. 